Effect of miR-939-5p on the migration and proliferation of hepatocellular carcinoma by regulating the expression of USP22 gene

Abstract

Objective To investigate the regulation of miR-939-5p on USP22 gene expression and its effect on liver cancer migration and proliferation. Methods The expression of miR-939-5p in hepatoma cell lines (HepG2, MHCC-97H, SMMC-7721, BEL-7404 and Huh7) and normal liver cell line LO2 was detected by real-time PCR (qPCR). The liver cancer cells with the lowest expression were used as experimental subjects, and transfected with miR-939-5p (Experimental group) or miR-NC (Control group). qPCR was used to detect the transfection efficiency of miR-939-5p. Transwell migration assay and MTT proliferation assay were used to detect the migration and proliferation of hepatoma cells after transfected miR-939-5p. Bioinformatics software predicted target genes for miR-939-5p. The dual luciferase reporter gene verified the interaction of miR-939-5p with the target gene. qPCR and Western blotting were used to detect the expression of target genes at mRNA and protein levels after over-expression of miR-939-5p. Measurement data were expressed as (Mean±SD), and t test was used for comparison between groups. Results The expression of miR-939-5p was significantly lower in hepatoma cell lines than in normal hepatocytes (P<0.01), and the expression of miR-939-5p was the lowest in SMMC-7721 cells (P<0.01). miR-939-5p was efficiently transfected into SMMC-7721 cells [(1.01±0.07) vs (20.12±1.27), P<0.01]. High expression of miR-939-5p inhibited the migration ability (P<0.01) and proliferative capacity of liver cancer SMMC-7721 cells (P<0.05). The USP22 gene may be a target gene of miR-939-5p. The luciferase reporter gene confirmed that miR-939-5p specifically binds to the 3′-UTR of USP22 mRNA (P<0.01). USP22 expression was decreased at mRNA and protein levels after high expression of miR-939-5p (P<0.01). Conclusions The expression of miR-939-5p was down-regulated in hepatocellular carcinoma cell lines, and miR-939-5p inhibited the migration and proliferation of liver cancer SMMC-7721 cells. The molecular mechanism was to interfere with the expression of USP22 gene. Key words: Liver neoplasms; Cell migration assays; Cell proliferation; microRNA; USP22